Photographic products and processes



Feb. 11, 1964 c, s ETAL 3,121,011

PHOTOGRAPHIC PRODUCTS AND PROCESSES Filed May 25, 1959 SILVER HALIDE EMULSION LAYER LAYER COMPRISING AN ALKALI- \k PERMEABLE POLYMER, A DYE DEVELOPER AND A HYDROPHOBIC W POLYMER SUPPORT FIG.I

BLUE-SENSITIVE SILVER HALIDE EMULSION LAYER COMPRISING AN ALKALI- PERMEABLE POLYMER, A YELLOW DYE DEVELOPER AND A HYDROPHOBIO POLYMER INTERLAYER {eazsn-seusmvs SILVER HALIDE F EMULSION I LAYER COMPRISING AN ALKAu I PERMEABLE POLYMER,A MAGENTA DYE DEVELOPER ANDA HYDROPHOBIO POLYMER A /INTERLAYER ESILLZIEONSITIVE SILVER HALIDE ///////////////*I LAYER COIIPRISINGANALKALI- I-\ PERMEABLE POLYMER,A OYAN DYE DEVELOPER ANDA HYDROPHOBIO POLYMER FIGZ SUPPORT IN VEN TOR-Y C.

3,121,011 PHQTOGRAPHIC PRQDUCTS AND PRGCESSES Howard C. Haas, Arlington, and Howard G. Rogers, Weston, Mass, assignors to Polaroid Corporation, Cambridge, Mass, a corporation of Deiaware Filed May 25, 1959, Ser. No. 815,545 4 Claims. (Cl. 9629) The present invention is concerned with photography and more particularly with novel photographic products and processes.

One object of this invention is to provide improved photosensitive elements for color diffusion transfer processes.

Another object of this invention is to provide color diffusion transfer processes utilizing said photosensitive elements.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order or one or more of such steps with respect to each of the others, and the product possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein:

FIGURE 1 is a diagrammatic cross-sectional view of one embodiment of a photosensitive element of this invention; and

FIG. 2 is a diagrammatic cross-sectional view of one embodiment of a multilayer photosensitive element within the scope of this invention.

The present invention is particularly related to color diffusion transfer processes. In such processes a photosensitive clement including a silver halide emulsion layer is exposed to create therein a latent image. The latent image is developed and, concurrent with and under the control of this development, an imagewise distribution of mobile color-providing substances is formed. At least a portion of these color-providing substances is transferred by means of an alkaline aqueous processing liquid to a superposed image-receiving layer to form a colored image thereon. As examples of such processes, mention may be made of the processes disclosed and claimed in the copending US. application of Howard G. Rogers, Serial No. 748,421, now Patent No. 2,983,606, filed July 14, 1958, as a continuation-in-part of US. application, Serial No. 415,073, filed March 9, 1954 (now abandoned), wherein dye developers (i.e., compounds which contain in the same molecule both the chromophoric system of a dye and also a silver halide developing function) are the color-providing substances, the processes disclosed and claimed in US. Patent No. 2,647,049, issued July 28, 1953, to Edwin H- Land, wherein color developers are employed to develop the latent image and color couplers are the color-providing substances, and the processes disclosed in US. Patent No. 2,774,668, issued December 18, 1956, to Howard G. Rogers, wherein complete, preformed dyes are used as the color-providing substances. The term color-providing substances, as used herein, refers to organic materials such as dyes, including dye developers, and dye intermediates.

In an especially useful mode of carrying outcolor diiiusion transfer processes, such as described above, the color-providing substances are disposed in a separate alkali-permeable layer in the photosensitive element. The separate alkali-permeable layer may be placed either in Patented Feta. 11, 1964 front of or behind the photosensitive emulsion with which it is associated; however, in a preferred embodiment it is placed behind, i.e., on the side of the emulsion which is most distant from the photographed subject when the emulsion is exposed, and preferably also adapted to be most distant from the image-receiving element when in superposed relationship therewith. In carrying out the processes, the photosensitive element is exposed and Wetted with an aqueous alkaline processing solution, for example, by immersing, coating, spraying, flowing, etc., in the dark, and the photosensitive element is superposed prior to, during or after wetting on an image-receiving element. In a preferred embodiment the aqueous alkaline processing solution contains a viscosity-increasing compound and is applied to the photosensitive element in a substantially uniform layer as the photosensitive element is brought into superposed position with the imagereceiving element. The alkaline aqueous processing solution permeates the photosensitive emulsion and alkalipermeable layers and solubilizes the color-providing substances to provide a substantially uniform distribution of the color-providing substances therein. As the processes proceed, the exposed silver halide image is developed and an imagewise distribution of mobile color-providing substances is formed. At least a portion of the colorproviding substances is transferred to and imbibed on the image-receiving element to form the image. The image is viewed by stripping the image-receiving element from the photosensitive element.

The term alkali-permeable, when used herein to describe the polymers in which the color-providing substances are disposed, refers to polymers which are permeated by aqueous alkaline solutions. In certain instances, the aqueous alkaline solutions may also contain an organic water-miscible solvent. The term is intended to cover polymers which are permeated by such solutions.

The polymers into which the color-providing substances are disposed, in addition to being alkali-permeable, are often hydrophilic in nature, i.e., they are solubilized, swelled, permeated, etc., by aqueous solutions. As examples of alkali-permeable polymers which have been found useful as carriers for the color-providing substances, mention may be made of cellulose acetate hydrogen phthalate; alkali metal, ammonia and amine salts of cellulose acetate hydrogen phthalate such as disclosed in the copending application of Howard C. Haas and Howard G. Rogers, Serial No. 815,546, filed May 25, 1959; copolymers of vinyl-phthalimide and (MS-unsaturated carboxylic acids such as those disclosed in the copending application of Howard C. Haas, Serial No. 781,009, now Patent No. 3,061,428, filed December 17, 1958; copolymers of N- vinylpyrrolidones and a,fiunsaturated carboxylic acids and terpolyme-rs of N-vinylpyrrolidones, a,,8-unsaturated carboxylic acids and alkyl esters of m d-unsaturated carboxylic acids such as those disclosed in the copending application of Howard C. Haas, Serial No. 781,007, now Patent No. 3,044,873, filed December 17, 1958; sulfobenzals of polyvinyl alcohol such as those disclosed in the copending application of Howard G. Rogers, Serial No. 781,008, filed December 17, 8; acylamidobenzene sulfo esters of partial sulfobenzals of polyvinyl alcohol such as those disclosed in the copending application. of Howard C. Haas and Howard G. Rogers, Serial No. 780,980, now Patent No. 3,043,692, filed December 17, 1958; copolymers of N,N-dialkyl-u,fit-unsaturated carboxamides with a,,B-unsaturated carboxylic acids and the amides of such acids and copolymers of N-aryland N-cycloalkyl-a,B-unsaturated carboxamides with c p-unsaturated carboxylic acids such as those discolsed in the copending application of Howard C. Haas, Serial No. 781,068, now Patent No.

3,069,264, filed December 17, 1958; poly-N-alkyl-a,,8- unsaturated carboxamides and copolymers of N-alkyl-u,;iunsaturated carboxamides with N-hydroxyalkyl-a,f3-unsaturated carboxamides such as those disclosed in the copending application of Howard C. Haas, Serial No. 780,979, now Patent No. 3,069,263, filed December 17, 1958; and dimethylhydantoin-formaldehyde condensation polymers.

When the color-providing substances are disposed in separate alkali-permeable layers, such as described above, minor irregular patterns, e.g., slight waviness, are sometimes observed in the transfer images which are produced. Such patterns, which detract only slightly from the good overall photographic quality of the image, appear to occur most frequently when aqueous coating solutions are used to apply the layers which are to be directly over the layers bearing the color-providing substances. Although the cause of such patterns is not known for certain, it is believed that in the coating operation the water of the coating solution permeates the layers and causes slight swellings and distortions which are transmitted to the transfer image. It has been discovered that such minor irregular patterns may be substantially eliminated by incorporating a small amount of hydrophobic polymer into the alkali-permeable layers.

The term hydrophobic polymer, as used herein, is intended to cover polymers which are insoluble and substantially non-swellable in aqueous solutions.

The amount of hydrophobic polymer which is added to the alkali-permeable layers may be varied to suit particular needs. Usually an amount equal to about 25%, by weight, of the alkali-permeable polymer will provide the desired results. As examples of hydrophobic polymers which are contemplated to be useful, mention may be made of cellulose acetate, cellulose nitrate, polyvinyl acetate, polyvinyl propionate, polyvinyl butyral, etc. Cellulose acetate and cellulose nitrate have been found to be particularly useful. It should be understood that the hydrophobic polymer should be compatible with the particular alkaliperrneable polymer used. Such compatibility can be readily determined by casting a simple test film.

The usefulness of the present invention is especially demonstrable when dye developers are the color-providing substances. Dye developers, as noted above, are compounds which contain in the same molecule both the chromophoric system of a dye and also a sliver halide developing function. By a silver halide developing function is meant a radical which is capable of developing an exposed silver halide image. Particularly useful dye developers are those in which the silver halide developing function is provided by the presence of benzenoid developing radicals in the compound. A preferred benzenoid developing radical in such compounds is a hydroquinonyl radical. Examples of representative dye developers are given in the previously mentioned US. application of Howard G. Rogers, Serial No. 748,421. Additional useful dye developers are described in the following copending U.S. applications:

Application Serial No. 449,514, now abandoned, replaced by S.N. 849,727, filed August 12, 1954, in the names of Elkan R. Blout and Myron S. Simon.

Application Serial No. 471,542, now abandoned, replaced by S.N. 1,443, filed November 26, 1954, in the names of Elkan R. Blout, Saul G. Cohen, Milton Green, Howard G. Rogers, Myron S. Simon and Robert B. lVoodward.

Application Serial No. 478,922, now abandoned, replaced by S.N. 824,785, filed December 30, 1954, in the names of Elkan R. Blout, Marilyn R. Cohler, Milton Green, Myron S. Simon and Robert B. Woodward.

Application Serial No. 612,045, now abandoned, replaced by S.N. 144,816, filed September 25, 1956, in the names of Elkan R. Blout, Milton Green and Howard G. Rogers.

Application Serial No. 612,052, now abandoned, replaced by S.N. 165,930, filed September 25, 1956, in the names of Milton Green and Howard G. Rogers.

'ing to procedures well known to the art.

Application Serial No. 612,05 3, now abandoned, replaced by SN. 196,523, filed September 25, 1956, in the name of Myron S. Simon.

Application Serial No. 612,054, now abandoned, replaced by S.N. 197,283, filed September 25, 1956, in the names of Helen P. Husek and Myron S. Simon.

Application Serial No. 612,055, now abandoned, replaced by S.N. 192,355, filed September 25, 1956, in the name of Helen P. Husek.

Application Serial No. 755,804, now abandoned, filed August 18, 1958, in the names of Elkan R. Blout, Saul G. Cohen, Milton Green and Myron S. Simon.

In color diffusion transfer processes employing dye developers, the dye developer, as mentioned previously for color-providing substances in general, is preferably placed in a separate alkali-permeable layer behind the photosensitive layer. Upon processing, the alkaline aqueous processing solution permeates to the separate alkalipermeable layer and solubilizes the dye developer therea from. As the process proceeds, the latent silver halide image in the photosensitive element is developed and, as a result of this development, the dye developer in the exposed areas is oxidized and substantially immobilized. At least a portion of the unreacted dye developer is imbibed on a superposed image-receiving element to create thereon the positive dye image. In such processes the immobilization of the dye developers in the exposed areas is apparently due, at least in part, to a change in the solubility characteristics of the dye developer upon oxidation. It may also be due in part to a tanning effect on the emulsion by the oxidized developer and to alkali exhaustion in the exposed areas.

FIG. 1 of the accompanying drawing illustrates one embodiment of a photosensitive element for use in color H diffusion transfer processes wherein a dye developer is disposed in an alkali-permeable layer containing a hydrophobic polymer. therein comprises a support 10, an alkali-permeable layer 12 comprising an alkali-permeable polymer, a dye dethis amount may be varied to suit particular needs. The

coating and drying operations may be carried out accord- The colorproviding substances which are to be disposed in the alkali-permeable-hydrophobic layers may be incorporated into the coating solution and applied therewith, or they may be imbibed onto the layers after their application. When the color-providing substances are incorporated into the coating solutions, they may be dispersed or solubilized therein depending upon the color-providing substance itself, the solvent used, and the state desired for the diffusion transfer processes. In a particularly useful embodiment the continuous phase of the layer, containing the color-providing substances, comprises a mixture of the alkali-permeable and hydrophobic polymers. Such an embodiment may be brought about by using as a solvent for the coating solution a material which is a solvent for both the alkali-permeable and hydrophobic polymers. Solvents for use in such coating solutions will vary depending upon the nature of the particular alkali-permeable and hydrophobic polymers which are to be used. A mixed solvent of ethanol and tetrahydrofuran has been found generally useful as a solvent for such solutions.

This invention is equally useful in preparing integral multilayer photosensitive elements for use in multicolor diffusion transfer precesses. As an example of such photosensitive elements, mention may be made of the photosensitive elements disclosed and claimed in the copending The photosensitive element shown of a blue-sensitive silver halide emulsion.

a US. application of Edwin H. Land and Howard G. Rogers, Serial No. 565,135, filed February 13, 1956, wherein at least two selectively sensitized photosensitive strata are superposed on a single support and are processed, simultaneously and without separation, with a single common image-receiving element. A suitable arrangement of this type comprises a support carrying a redsensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum, and a blue-sensitive silver halide emulsion stratum, said emulsions having associated therewith, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer. In one of the preferred embodiments of photosensitive elements of this type, the dye developers are disposed in separate alkaliperrneable layers behind the photosensitive silver halide emulsion stratum with which they are associated. As in monochromatic photosensitive elements, the addition of a small amount of hydrophobic polymer to the layers containing the color-providing substances substantially eliminates the irregular patterns which are sometimes produced in the transfer images.

A multilayer photosensitive element of the type mentioned above is illustrated in FIG. 2 of the accompanying drawing. A support 20 carries a layer 22 comprising an alkali-permeable polymer, a cyan dye developer and a hydrophobic polymer; a layer 24 of a red-sensitive silver halide emulsion; an interlayer 26; a layer 28 comprising an alkali-permeable polymer, a magenta dye developer and a hydrophobic polymer; a layer 30 of a green-sensitive silver halide emulsion; an interlayer 32; a layer comprising an alkali-permeable polymer, a yellow dye developer and a hydrophobic polymer; and an outermost layer 36 In certain instances, for example when the yellow dye developer is not present in a state capable of functioning as a filter, a yellow filter is placed in inter-layer 32.

Both the monochromatic and multicolor photosensitive elements within the scope of this invention may be used in picture roll units which contain a plurality of photosensitive frames. The photosensitive elements of this invention are especially useful in composite picture rolls intended for use in a Polaroid Land Camera, sold by Polaroid Corporation, Cambridge 39, Massachusetts, or a similar camera structure such, for example, as the camera forming the subject matter of US. Patent No. 2,435,717, issued to Edwin H. Land on February 10, 1948. In general, such composite picture rolls comprise a photosensitive roll, a roll of image-receiving material and a plurality of pods containing an aqueous alkaline processing solution. The rolls and pods are so associated with each other that, upon processing, the photosensitive element may be superposed on the image-receiving element and the pods may be ruptured to spread the aqueous alkaline processing solution between the superposed elements. The nature and construction of the pods used in such units are well known to the art. See, for example, US. Patent Nos. 2,543,181 and 2,634,886, issued to Edwin H. Land.

The following nonlirniting examples illustrate the preparation and use of photosensitive elements within the scope of the invention:

Example 1 A methanol-tetrahydrofuran coating solution (1 to l, by volume) comprising 1.5% of a N,N-diethylacrylamideacrylic acid copolymer (initial polymer produced from reaction mixture having a molar ratio of N,N-diethylacrylamide monomer to acrylic acid monomer of 7 to 3), 0.5% cellulose nitrate and 3.0% of 1-phenyl-3-N-n-hexylcarboxarnido 4 [p (2',5'-dihydroxyphenethyl)-phenylazo]--pyrazolone (a yellow dye developer prepared in a manner similar to that disclosed in the previously mentioned copending U.S. application, Serial No. 612,045) was coated on a gelatin-subcoated cellulose acetate support. When the coating solution had dried, an aqueous silver halide emulsion coating solution was applied.

The above photosensitive element was exposed and then processed by spreading an aqueous processing solution comprising Percent Sodium carboxymethyl cellulose 5.0 Sodium hydroxide 2.0 1-phenyl-3-pyrazolidone 0.6 2,S-bis-ethyleneiminohydroquinone 0.4 6-nitrobenzimidazole 0.12

between said photosensitive element and an image-receiving element as said elements were brought into superposed relationship. The image-receiving element comprised a cellulose acetate-coated baryta paper which had been coated with an ethanol solution containing 4% of a N- methoxymethyl polyhexamethylene adipamide polymer. After an imbibition period of approximately one minute, the image-receiving element was separated and contained a dense yellow positive dye image of the photographed subject. No irregular patterns were observed.

Example 2 A photosensitive element was prepared in a manner similar to that employed in Example 1 except that a dimethylhydantoin-formaldehyde condensation polymer was used in place of the N,N-diethylacrylamide-acrylic acid copolymer. Upon processing, in a manner similar to that employed in Example 1, a dense yellow transfer image was obtained and no irregular patterns were observed.

As mentioned previously, this invention is equally useful in multicolor and multilayer photosensitive elements such as those disclosed in the previously mentioned copending application, Serial No. 748,421. Such multilayer photosensitive elements may be made, for example, by successively coating a gelatin-subcoated cellulose acetate support with appropriate coating solutions such, for exa1nple, as the following:

(1) A tetrahydrofuran-methanol solution (1 to 1, by volume) comprising 5.5% of 1,4-bis-[u-methyl-B-(2,5'- dihydroxyphenyl)-ethylamino] -anthraquinone (a cyan dye developer prepared in a manner similar to that disclosed in the previously mentioned copending application, Serial No. 478,922), 2.0% of a N,N-diethylacrylamide-acrylamide coplymer (the initial polymer produced from a re action mixture comprising 7 mole parts of N,N-diethylacrylamide monomer to 3 mole parts acrylamide monomer) and 0.5% of cellulose acetate or cellulose nitrate.

(2) A red-sensitive silver iodobromide emulsion coating solution.

(3) An acetone solution comprising 2.0% of cellulose acetate hydrogen phthalate and 0.75% cellulose acetate.

(4) A 2.0% aqueous polyvinyl alcohol solution containing a small amount of a nonionic wetting agent.

(5) A tetrahydrofuran-methanol solution (1 to 1, by volume) comprising 3.5% of 2-[p-(2',5'-dihydroxyphenethyl) -phenylazo]-4-n-propoxy-1-naphthol (a magenta dye developer prepared in a manner similar to that disclosed in the previously mentioned copending application, Serial No. 612,045), 2.0% of a N,N-diethylacrylamideacrylarnide copolymer (as in solution 1) and 0.5% of cellulose acetate or cellulose nitrate.

(6) A green-sensitive silver iodobromide emulsion coating solution.

(7) An acetone solution comprising 2.0% cellulose acetate hydrogen phthalate and 0.5 cellulose acetate.

(8) A 2.0% aqueous polyvinyl alcohol solution containing a small amount of a nonionic wetting agent.

(9) A tetrahydrofuran-methanol solution (1 to 1, by volume) comprising 3.0% of l-phenyl-3-N-n-hexyl-carbamyl 4 [p (2,5'-dihydroxyphenethyl)-phenylazo] -5- pyrazolone (a yellow dye developer prepared in a manner similar to that disclosed in the previously mentioned copending application, Serial No. 612,045 2.0% of a N,N- diethylacrylamide-acrylamide copolymer (as in solution 1) and 0.5% of cellulose acetate or cellulose nitrate.

(10) A blue-sensitive silver iodobromide emulsion coating solution.

Multilayer photosensitive elements, such as described above, may be processed, after exposure, by spreading a processing solution such, for example, as an aqueous solution comprising:

Percent Sodium hydroxide 3.0 Sodium carboxymethyl cellulose 5.0 1-phenyl-3 -pyrazolidone 1 .2 2,5-bis-ethyleneiminohydroquinone 0.9 6-nitrobenzirnidazole 0.12

between the photosensitive element and an image-receiving element and imbibing for approximately three minutes.

This invention is further suitable for use in screen type photosensitive elements such as disclosed in the aforementioned application of Howard G. Rogers, Serial No. 748,421 and also the copending application of Edwin H. Land, Serial No. 448,441, now Patent No. 2,968,554, filed August 9, 1954, wherein at least two selectively sensitized silver halide emulsions are arranged in the form of a screen and the color-providing substances, as in multilayer photosensitive elements, are preferably placed in a separate alkali-permeable layer in back of the photosensitive emulsion with which they are associated.

The present application is a continuation in part of our application Serial No. 780,980, filed December 17, 1958, and now US. Patent No. 3,043,692, issued July 10, 1962.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. The process of forming transfer images in color which comprises exposing a photosensitive element including a silver halide emulsion layer and a polymeric layer contiguous with said silver halide emulsion, said polymeric layer comprising an alkali-permeable polymer and containing a dye developer, applying an aqueous alkaline processing solution to said photosensitive element, soluhilizing at least a portion of said dye developer from said polymeric layer, developing the exposed emulsion in the presence of said dye developer whereby said developer is immobilized in exposed areas but is mobile in unexposed areas in said emulsion and transferring at least a portion of said mobile dye developer to a 1,3 superposed image-receiving layer to form a positive image thereon, said polymeric layer comprising a second polymer selected from the group consisting of cellulose nitrate and cellulose acetate, said second polymer and said alkali-permeable polymer being intimately mixed and forming the continuous phase of said polymeric layer, said alkali-permeable polymer being selected from the group consisting of copolymers of vinyl pht-halimide and 7 an a d-unsaturated carboxylic acid; COPOlYIRCJS of N- vinylpyrroiidone and an u,,8-unsaturated carboxylic acid; terpolymers of N-vinylpyrrolidone, an e,,8-unsatruated carboxylic acid an an alkyl ester of an u,B-unsaturated carboxylic acid; sulfobenzals of polyvinyl alcohol; acylamidobenzene sulfoesters of partial sulfobenzals of polyvinyl alcohol; copolymers of N,N-dialky1-a,,B-unsaturated carboxarnide and a comonomer selected from the group consisting of v c-unsaturated carboxylic acids and the amides of such acids; copolymers of an cad-unsaturated carboxylic acid and a comonomer selected from the group consisting of N-cycloalkyl and N-aryl-afi-unsaturated carboxamides; poly N alkyl a,/8-unsaturated carboxamides; copolymers of N-alkyl-a,B-unsaturated carbox amides with an N-hyd-roxyalkyl-nap-unsaturated carboxamide, and a condensation polymer of dimethylhydantoin and formaldehyde.

2. A process as defined in claim 1 wherein said alkalipermeable polymer is a copolymer of N,N-diethylacrylamide and acrylic acid and said second polymer is cellulose acetate.

3. A process as defined in claim 1 wherein said alkalipermeable polymer is a condensation polymer of dimethylhydantoin and formaldehyde and said second polymer is cellulose acetate.

4. A process as defined in claim 1 wherein said alkalipermeable polymer is a copolymer of l LN-diethylacrylamide and acrylamide and said second polymer'is cellulose acetate.

References Cited in the file of this patent UNITED STATES PATENTS 2,210,146 Eggert et al Aug. 8, 1940 2,267,689 Eggert et al Dec. 23, 1941 2,304,940 Marines et a1. Dec. 15, 1942 2,698,798 Land Jan. 4, 1955 2,983,606 Rogers May 9, 1961 2,992,164 Haas July 11, 1961 OTHER REFERENCES I. Am. Pharm. Assn., Sci. Edn, vol. 40', No. 10, 1951, pages 520-525. 

1. THE PROCESS OF FORMING TRANSFER EMAGES IN COLOR WHICH COMPRISES EXPOSING A PHOTOSENSITIVE ELEMENT INCLUDING A SILVER HALIDE EMULSION LAYER AND A POLYMERIC LAYER CONTIGUOUS WITH SAID SILVER HALIDE EMULSION, SAID POLYMERIC LAYER COMPRISING AN ALKALI-PERMEABLE POLYMER AND CONTAINING A DYE DEVELOPER, APPLYING AN AQUEOUS ALKALINE PROCESSING SOLUTON TO SAID PHOTOSENSITIVE ELEMENT, SOLUBILIZING AT LEAST A PORTION OF SAID DYE DEVELOPER FROM SAID POLYMERIC LAYER, DEVELOPING THE EXPOSED EMULSION IN THE PRESENCE OF SAID DYE DEVELOPER WHEREBY SAID DEVELOPER IS IMMOBILIZED IN EXPOSED AREAS BUT IS MOBILE IN UNEXPOSED ARES IN SAID EMULSION AND TRANSFERRING AT LEAST A PORTION OF SAID MOBILE DYE DEVELOPER TO A SUPPERPOSED IMAGE-RECEIVING LAYER TO FORM A POSITIVE IMAGE THEREON, SAID POLYMERIC LAYER COMPRISING A SECOND POLYMER SELECTED FROM THE GROUP CONSISTING OF CELLULOSE NITRATE AND CELLULOSE ACETATE, SAID SECOND POLYMER AND SAID ALKALI-PERMEABLE POLYMER BEING SELECTED FROM THE GROUP CONSISTING OF COPOLYMERS OF VINYL PHTHALIMIDE AND 